The other big problem that people overlook is that MIDI over USB is NOT a standard that has been defined by the MIDI Manufacturers Association. Devices with USB MIDI can only be used with a computer that is running that manufacturer's device driver that understands how MIDI data is to be received and transmitted over the USB connection. Even if all MIDI gear came equipped with USB MIDI ports you could not plug a Roland USB connection into a Yamaha USB connection. While the cable would fit neither keyboard would understand the other. So MIDI communication between keyboards without a computer would become a thing of the past .... that would be very very bad and is completely against the whole point of establishing a MIDI standard in the very beginning.
[This message has been edited by Nigel (edited 08-06-2008).]